I work under a variety of licenses, from the very permissive (MIT) to the middling (LGPL) to the downright restrictive (RPL). You can always use my code under the license I chose to release it, but for various reasons, you may want to license it commercially instead:
For all these and more, contact me directly. I don't have a price list, because every situation and project is different, but I'd like to have something for everyone, whether you're indie or enterprise.
This offer is good for any software where I have relicensing rights. Which is a lot of them.
Maybe. Especially if your project is an open source project with an active community that will help me find bugs and improve my software too. If this is you, ask me about it. My licensing choices are pragmatic, not ideological.
Sometimes, though, this is said by people who want to use my software and not give anything back. People should always give back to software they use. That's why I offer commercial licensing; you can give back by paying for the software.
I'm not a lawyer and I can't give you legal advice. You should be asking your lawyer if you're allowed to do X or not. There are also plenty of position statements written by lawyers about software licenses that are freely available online.
If you want absolute certainty about X, it might be best to get a commercial license that clearly says "you can do X".
If you're a software developer willing to contribute important features, in many cases I'd be happy to give you commercial usage rights in exchange for your contributions. Contact me to talk about it.